The present invention generally relates to firearms, and more particularly to firing control mechanisms for revolvers having trigger-actuated cockable hammers.
Conventional revolvers generally include a frame which supports a rotatable cylinder having a plurality of chambers adapted for holding cartridges, a barrel, and a firing control mechanism including a hammer and a trigger pivotally mounted to the frame for operating the hammer. In double-action revolvers, the trigger is operable via a single continuous rearward pull by the user that both fully cocks and then releases the hammer to discharge the revolver.
Conventional trigger designs are generally described in U.S. Pat. Nos. 3,628,278 and 4,307,530, which are each incorporated herein by reference in their entireties. FIG. 5 of U.S. Pat. No. 3,628,278 is reproduced herein as FIG. 1. The trigger 7 is pivotally mounted to the revolver frame about a pivot pin 39. The trigger includes a rear operating extension 42 that projects in a rearward direction towards the pivotally mounted hammer 6. A trigger spring (not shown) biases the trigger forward in a clockwise direction (as viewed in FIG. 1). A spring-loaded lever, generally referred to as a hammer dog 36, is pivotally mounted to the hammer for cocking the hammer. The hammer dog 36 is engaged by rear operating extension 42 of the trigger. Pulling the trigger 7 rearward causes the trigger and operating extension to rotate in a counterclockwise direction, which engages and rotates the hammer dog 36 in a clockwise direction. This concomitantly rotates the hammer 6 clockwise against the forward biasing force of the hammer mainspring 32. The hammer eventually reaches a fully cocked rearward position, and is then released by the trigger. The hammer rotates forward in a counterclockwise direction to in turn contact and drive a firing pin 35 forward which strikes and detonates a chambered cartridge.
When firing a double action revolver, the user must apply sufficient finger pull pressure to the trigger to overcome at least the forward biasing effect of both the trigger spring and the hammer main spring. In addition, friction between mating surfaces on the rear operating extension of the trigger and the hammer dog must be overcome by the trigger pull. Due to the operational interaction and geometrical arrangement between the meshing surfaces of the trigger and hammer dog used heretofore, trigger action in conventional revolver firing control mechanisms has generally been characterized by uneven trigger pull resistance over the trigger's full range of motion. As shown in the graph in FIG. 2, conventional known trigger mechanisms typically require initially higher peak or maximum trigger pull pressure or force by the user during the first portion of rearward range of motion of the trigger. The trigger pull pressure or force requirements then level off followed by a sometimes sharp or abrupt decrease in magnitude as the trigger is continued to be pulled fully rearward by the user through hammer release. This phenomenon causes the revolver to jump or jerk momentarily, which may make it more difficult for some users to steady the firearm and keep it aimed precisely on target down range. In addition, the generally high peak trigger pull force requirements and non-uniform pull force give conventional double action revolver trigger mechanisms their characteristically heavy trigger pull, which may make using such revolvers more cumbersome for some users.
An improved firearm trigger mechanism is therefore desired.